A 0.9-V pulse frequency modulation photosensor based on capacitive feedback reset

Koutaro Yasuoka; Keiichiro Kagawa; Jun Ohta; Masahiro Nunoshita

doi:10.1117/12.588226

7 March 2005 A 0.9-V pulse frequency modulation photosensor based on capacitive feedback reset

Koutaro Yasuoka, Keiichiro Kagawa, Jun Ohta, Masahiro Nunoshita

Proceedings Volume 5677, Sensors and Camera Systems for Scientific and Industrial Applications VI; (2005) https://doi.org/10.1117/12.588226
Event: Electronic Imaging 2005, 2005, San Jose, California, United States

Abstract

We are developing a retinal prosthesis vision chip based on a pulse-frequency-modulation (PFM) photosensor. Because the device is implanted in the eye ball and is powered by RF coil coupling with limited energy, low voltage and small current operation is required to achieve low power dissipation. We propose a capacitive-feedback-reset method for the PFM vision chip. The proposed method uses capacitive feed back through the junction capacitance of the photodiode and gate-source overlap capacitance of the reset transistor. In the proposed PFM circuit, the feed-through effect in resetting contributes to avoid current competition, so that the high dynamic range can be achieved even at the low voltage operation. We have fabricated a pixel TEG circuit in a 0.35-μm CMOS technology. The PFM photosensor circuit is composed of a four-stage inverter-chain. Dynamic range of 136dB has been achieved with 0.8-V power supply.

Citation Download Citation

Koutaro Yasuoka, Keiichiro Kagawa, Jun Ohta, and Masahiro Nunoshita "A 0.9-V pulse frequency modulation photosensor based on capacitive feedback reset", Proc. SPIE 5677, Sensors and Camera Systems for Scientific and Industrial Applications VI, (7 March 2005); https://doi.org/10.1117/12.588226

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